EB-GD55 Rings at midnight??????

I recently purchased a EB-GD55 triband GSM phone for use in the Bahamas/US/Europe.
The phone is unlocked, is not subscribed and has no SIM card.
I charged the battery and set the time
Now, the phone rings at midnight every night for about a minute.
How come a non subscribed turned off phone with no SIM card rings at midnight?
Thanks

maybe its an alert tone of some sort?